Production of L-isoleucine, L-valine and other amino acids via fermentation has been the subject of considerable research. Numerous genera of microorganisms have been employed along with various analogues of L-isoleucine, threonine, valine, etc. From U.S. Pat. No. 3,893,888 it is known that L-valine can be produced from mutant strains of Brevibacterium resistant to .alpha.-amino-.beta.-hydroxy valeric acid (AHV). The biosynthetic pathways in Brevibacterium for production of L-isoleucine using ethionine and AHV as antagonists have also been studied. See:
Ikeda, S., I. Fujita and Y. Hirose. (1976). Culture conditions of L-isoleucine fermentation from acetic acid. Agr. Biol. Chem., 40(3), 517-522. PA1 Ikeda, S., I. Fugita and F. Yoshinaga. (1976).Screening of L-isoleucine producers among ethionine resistant mutants of L-threonine producing bacteria. Agr. Biol. Chem., 40(3), 511-516. PA1 Shiio, Isamu, A. Sasaki, S. Nakamori and K. Sano. (1973). Production of L-isoleucine by AHV resistant mutants of Brevibacterium flavum. Agr. Biol. Chem., 37(9), 2053-2061. PA1 Szentirmai, A. and I Horvath. (1976). Regulation of branched-chain amino acid biosynthesis. Acta Microbiol. Acad. Sci. Hung., 23, 137-149. PA1 Umbarger, H. E. (1974). The elements involved in the multivalent regulation of the isoleucine and valine biosynthetic enzymes of the enterobacteriaceae. Proceedings of the 1st. Intersectional Congress of IAMS, 1, Tokyo. PA1 Umbarger, H. E. (1973). Genetic and physiological regulation of isoleucine, valine and leucine formation in the Enterobacteriaceae. From "Genetics of Industrial Microorganisms".
Several general articles on biosynthetic pathways for producing L-isoleucine as well as other amino acids have also been published. See:
The biosynthetic pathway for production of L-isoleucine in Serratia marcescens has also been extensively studied using various antagonists such as isoleucine hydroxamate, and .alpha.-aminobutyric acid. Pathways for L-isoleucine production in E.coli have also been studied using antagonists such as thiaisoleucine. Alpha-aminobutyric acid has also been employed as an antagonist in studying L-isoleucine production in Bifidobacterium. L-isoleucine production has also been studied in microorganisms of the genus Pseudomonas, Salmonella (using 5.sup.1,5.sup.1,5.sup.1 -trifluoroleucine as an antagonist) and in Streptomyces rimosus.
In addition to those described above, numerous processes have been patented for the production of L-isoleucine. See U.S. Pat. No. 3,058,888 (Pseudomonas strains requiring .alpha.-aminobutyric acid); U.S. Pat. No. 3,231,478 (Brevibacterium requiring threonine); U.S. Pat. No. 3,262,861 (Brevibacterium requiring .alpha.-aminobutyric acid); U.S. Pat. No. 3,532,600 (Arthrobacter citreus requiring .alpha.-aminobutyric acid); U.S. Pat. No. 3,671,396 (Brevibacterium requiring .alpha.-aminobutyric acid, .alpha.-hydroxybutyric acid or threonine) and U.S. Pat. No. 3,841,968 (Serratia marcescens requiring L-threonine, L-homoserine or L-aspartic acid with resistance to isoleucine hydroxamate and/or .alpha.-aminobutyric acid).